Concerning the clusters, from observations made during investigations of the start of the outbreak in some countries [1]}, [2]}, [3]}, [4]}, [5]}, [6]}, [7]}, [8]}, [9]}, [10]}, [11]}, [12]}, [13]}, [14]}, it is possible to get spatial and temporal information on the start of the epidemic, but these studies rarely allow the estimation of the parameters \(S_0\)  and \(\tau \)  in the concerned population and worse, they give no indication of how long they remain constant. Here we assumed that they remained constant only during the period of exponential growth of new cases observed.
